How do you build a recursive program in C plus plus for pascals triangle?

#include<iostream>

#include<string>

int pascal (const int row, const int col)

{

if (!col col==row)

return 1;

return pascal (row-1, col-1) + pascal (row-1, col);

}

int main()

{

using namespace std;

cout << "Enter a row number for Pascal's Triangle: ";

size_t rows;

cin >> rows;

for (size_t row=0; row!=rows; ++row)

{

cout << string (rows-row,'\t');

for(size_t col=0;col<=row; ++col)

cout << pascal (row,col) << "\t\t";

cout << endl;

}

}